Question

Define Congenital Megacolon

Answer 1

This anomaly, also called Hirschsprung's disease, is character­ized by abnormal dilatation of a seg­ment of the colon; the dilated segment is called megacolon. However, the pri­mary congenital defect is not in the di­lated .part of the colon but in the seg­ment of the large intestine distal to the dilated part. The primary defect in Hirschsprung's disease has been found to be the absence of parasympathetic ganglion cells in the submucosal and myenteric nerve plexuses of the gut wall. This aganglionosis is attributed to the failure of migration of ganglion cells from the neural crest to the wall of the affected part of the large intestine. In majority of the cases of Hirschsprung's disease the rectum and adjacent part of the sigmoid colon are found to be affected by aganglionosis. Lack of peri­stalsis in the aganglionic segment of the large gut results in a functional in­testinal obstruction. The classic symp­toms of Hirschsprung's disease are constipation and abdominal distension after birth. The part of the colon proxi­mal to the aganglionic segment is his-tologically normal but, because of ob­struction, becomes greatly distended and hypertrophied. Congenital megacolon is more frequent in males
and familial cases are common. Un­treated patients of Hirschsprung's dis­ease die of intestinal infection. The treatment is surgical excision of the aganglionic segment of the large intes­tine.